[单选题]The livestock’s outsize impacts have become more prominent in environmental 1______lately and for good reason. Beef and dairy are 2______for more greenhouse gas emissions than any other food source by a long shot, largely 3______methane from cattle’s digestion, emissions from manure, and the 4______of carbon-rich forest to pasture and cropland for animal feed. While the development of meat and dairy 5______,such as plant-based meat, is helping shift diets in rich countries, the world is still 6______more beef and milk every year.As emerging economies grow, we can expect their beef consumption to follow in 7______. While this increase signals that more people are able to afford richer, more varied diets, it 8______grim prospects for the climate.But there’s a 9______story as well—one that is underappreciated and provides hope that livestock’s impact can be reduced: the story of peak pasture. In the past 20 years,something 10______has occurred, something few predicted: after several centuries of expansion, global pasture area has begun to 11______. According to the United Nations’ most recent data, there are a 12______140 million fewer hectares of pasture than there were in 2000, an area roughly the size of Peru.Because pasture is one of the largest 13______of deforestation in many regions—and of the habitat loss and carbon 14______that follow—this is good news for the environment. This positive trend has a strikingly simple explanation: rising 15______of pasture land and livestock.Thanks to modern breeding efforts and more resource-efficient 16______, the world is producing a greater 17______of meat and milk than ever before, even as pasture area has shrunk.Average global beef production per cow, for instance,has grown about 30 percent since 1961, and land managers across continents have begun growing specific grasses for cattle to eat that can 18______production severalfold. Analogous to the green revolution of the 20th century that brought unprecedented levels of crop productivity, it’s fair to say that the world has undergone a "livestock revolution"—not the whole world, however.Most notably, productivity remains low in sub-Saharan Africa, where widespread overgrazing 19______the quality of grazing land.Rapid population and economic growth in the region, 20______persistently low productivity, could augur a major re-expansion of global pasture. 第1题答案是______。